In certain polymerization processes, liquid or gaseous monomer is polymerized in the presence of a diluent in which the polymerization product is not appreciably soluble. As a result, a slurry is formed in which the solid polymerization product is dispersed in the form of polymer particles or agglomerates. In many of these processes, the diluent facilitates heat transfer away from the polymer agglomerates.
While these processes are technologically useful, these polymerization processes present several challenges. To begin with, the resultant slurry may have a relatively high viscosity, which inhibits mixing and heat transfer, and which can negatively impact polymer properties, reactor operability, and may cause reactor fouling. This relatively high viscosity also places practical limitations on the solids content of the polymer being produced. Also, since the reaction takes place in the presence of a diluent, there is a need to separate the polymer and polymer agglomerates from the diluent and ultimately deliquify and dry the polymer product.
As the skilled person appreciates, polymerizations of this nature are typically conducted within continuously-stirred tank reactors using adequate volumes of diluent and mixing to maintain fluid conditions. Following polymerization, the diluent, which is often an organic solvent, is removed by conventional solvent stripping techniques. For example, the solvent may be stripped from the polymerization product by using steam desolventization techniques, which produces a wet product that must be dried.
These conventional processes, as well as the equipment used in these processes, can be energy intensive and costly. There is, therefore, a need for systems in which slurry polymerizations can be efficiently conducted.